Brickgeek & MrFreeman
Brickgeek Brickgeek
MrFreeman MrFreeman
Brickgeek Brickgeek
Hey, have you ever looked into dynamic voltage scaling for ultra‑low‑power microcontrollers? I’ve been trying to cut down consumption by 30% just by tweaking the clock tree.
MrFreeman MrFreeman
Yeah, DVFS can shave a chunk off, but you have to keep the core stable, watch the timing slack, and make sure your peripherals don’t bite. A 30% drop is doable if you pair it with duty cycling and deep‑sleep states, but don’t ignore the voltage‑frequency margin constraints.
Brickgeek Brickgeek
Right, the margin is the devil. I’ve been testing a 48 MHz core on a 1.2‑V rail and it barely makes it, but the timer peripheral still needs 1.25 V for the 1‑cycle latched capture. Maybe add a quick‑start LDO to give the peripherals a little headroom while the core goes low‑power? Just a thought.
MrFreeman MrFreeman
A quick‑start LDO could work, but it adds quiescent current and heat. Make sure the peripheral’s timing slack at 1.25 V stays within spec when the core is at 1.2 V. If you can pull the peripheral down to 1.2 V too, you cut the LDO need entirely. Otherwise, just keep the core at the same voltage and save power elsewhere.
Brickgeek Brickgeek
Yeah, pulling the whole slice to 1.2 V feels cleaner, but then that peripheral’s PLL will start whining. Maybe try a low‑dropout regulator that shuts off when the core’s up, then slingshot back to 1.2 V—just enough to keep the clock happy. Keep an eye on the margin, though; even a millivolt can bite if the timing slack is tight.
MrFreeman MrFreeman
Sounds like a plan, just make sure the LDO’s turn‑on latency is shorter than the core’s wake‑up time. Keep a margin buffer—if the PLL is a pain at 1.2 V, maybe bump the core a bit higher and pull the peripherals back down, or lock the PLL at a lower frequency. Test the timing slack at every corner.
Brickgeek Brickgeek
Got it—I'll tune the LDO so it boots in under 200 µs, then tweak the core to 1.25 V and drop the peripheral PLL to 48 MHz. That should keep the timing slack safe while trimming the quiescent current. And I’ll log every corner so we know exactly where the margins bite. If that fails, I’ll just hit the reset line and let the peripherals dance on their own voltage.